A Wolf’s Place – Annie White (2013)

Ecological theory predicts that by keeping herbivore populations under check predators can indirectly enhance growth of vegetation and can even alter local climate. The influential ecologist Robert Paine has demonstrated this phenomenon of keystone species on predatory starfishes and sea otters maintaining species diversity in coastal rocky communities in Washington.

Directed and produced by Annie White, “A Wolf’s Place” tells the story of wolf reintroduction to Yellowstone national park in 1995. Wolves became locally extinct in much of the United States in 20th Century. The niche left abandoned by wolves rapidly became occupied by coyotes however this was not sufficient to keep large herbivore populations down. Gradually Yellowstone drifted into a different ecosystem.

The documentary also tells the story of Wolf #10, the first wild wolf released into Yellowstone in over 70 years – his triumphant life and his tragic death in the sights of a poacher’s gun.

How Wolves Change Rivers from Sustainable Human on Vimeo.

Wolves indeed brought about an enormous change in Yellowstone. They reduced browsing and as a consequence there was more vegetation especially along the river banks which in turn resulted in a trophic cascade. Increasing willow abundance along rivers provided food and construction material for beavers. Beaver activity slowed down hydrology, reduced silt and enhanced water retention capacity of the ecosystem. Increased water table invigorates vegetation. At the same time reduced sun exposure of rivers allows cold water adapted fish to thrive. Cold waters in deeper layers of beaver ponds are particularly valuable rearing habitat for Coho salmon.

Predators not only put a dent on herbivore numbers, but also reduce their feeding efficiency. Sheer presence of a predator induces fear and make the herbivores more vigilant. “Ecology of the fear” is a defining term for the rippling effects of the presence of predators in a habitat. These changes can even be physiological as observed in tail and muscular changes in frog tadpoles and guppy fishes. Presence of predators affect the developmental strategies of many amphibians and fishes.

Land of the Bears (Kamchatka) – Guillaume Vincent (2013)